Determinants of precocious B-cell aging in European adolescences living with perinatally acquired HIV-1 after over 10 years of suppressive therapy

HIV infection results in a state of chronic immune activation leading to premature immune aging, B-cells dysfunction, that persists despite prolonged virological suppression. In this scenario, adolescence living with perinatally acquired HIV (PHIV), deserve a peculiar attention since potentially exposed for their entire life to chronic immune activation. Here we identified determinants of precocious aging B cells in 40 PHIV undergoing suppressive antiretroviral therapy (ART) for median 13.5 years. All individuals started ART by 2 nd year of life and achieved virus suppression within the 1 st year of ART, with majority of patient maintaining suppression until analysis and 5/40 experiencing viral Spike (transient elevation of HIV-1 VL, 50-999 copies/ml). We employed a multi-omics approach including deep immunological B and T cell phenotype in PBMC, with aging B cells defined by the expression of T-bet and CD11c; plasma proteomics analysis by mass spectrometry and serum level of anti-measles antibodies as correlates of humoral response. We found that individuals with expansion of aging B cell, defined by the expression of T-bet+CD11c+, were those starting treatment later, presenting detectable levels of cell-associated HIV-1 RNA, history of Spikes, and a higher frequency of exhausted T-cells, including those expressing PD-1, LAG3, TIGIT. Accordingly, the proteomic analysis revealed that subjects with expansion of aging B cells and exhausted T cells had enrichment of proteins involved in immune inflammation and complement activation pathways, such as CLU and APCS which are also involved in tumor progression. Signs of precocious aging were associated with a reduced capacity to maintain virological memory against measles vaccination. To our knowledge, this is the first study focusing on precocious B-cell aging and dysfunctionality in PHIV with long-term virological suppression. Our experimental strategy enabled identification of clinical, viral, cellular and plasma soluble markers associated with B-cells aging. Our results pave the way to further define risk of disease progression or lymphoproliferative disorders in PHIV.

Myeloid-derived suppressor cells and the pathogenesis of human immunodeficiency virus infection

There are several mechanisms by which human immunodeficiency virus (HIV) can mediate immune dysfunction and exhaustion during the course of infection. Chronic immune activation, after HIV infection, seems to be a key driving force of such unwanted consequences, which in turn worsens the pathological status. In such cases, the immune system is programmed to initiate responses that counteract unwanted immune activation, for example through the expansion of myeloid-derived suppressor cells (MDSCs). Although the expansion of immune suppressor cells in the setting of systemic chronic immune activation, in theory, is expected to contain immune activation, HIV infection is still associated with a remarkably high level of biomarkers of immune activation. Paradoxically, the expansion of immune suppressor cells during HIV infection can suppress potent anti-viral immune responses, which in turn contribute to viral persistence and disease progression. This indicates that HIV hijacks not only immune activation but also the immune regulatory responses to its advantage. In this work, we aim to pave the way to comprehend how such unwanted expansion of MDSCs could participate in the pathology of acute/primary and chronic HIV infection in humans, as well as simian immunodeficiency virus infection in rhesus macaques, according to the available literature.

HIV-Related Immune Activation and Inflammation: Current Understanding and Strategies

Although antiretroviral therapy effectively controls human immunodeficiency virus (HIV) replication, a residual chronic immune activation/inflammation persists throughout the disease. This aberrant immune activation and inflammation are considered an accelerator of non-AIDS-related events and one of the driving forces of CD4+ T cell depletion. Unfortunately, HIV-associated immune activation is driven by various factors, while the mechanism of excessive inflammation has not been formally clarified. To date, several clinical interventions or treatment candidates undergoing clinical trials have been proposed to combat this systemic immune activation/inflammation. However, these strategies revealed limited results, or their nonspecific anti-inflammatory properties are similar to previous interventions. Here, we reviewed recent learnings of immune activation and persisting inflammation associated with HIV infection, as well as the current directions to overcome it. Of note, a more profound understanding of the specific mechanisms for aberrant inflammation is still imperative for identifying an effective clinical intervention strategy.

Chronic Immune Activation and CD4+ T Cell Lymphopenia in Healthy African Individuals: Perspectives for SARS-CoV-2 Vaccine Efficacy

Chronic immune activation has been considered as the driving force for CD4+ T cell depletion in people infected with HIV-1. Interestingly, the normal immune profile of adult HIV-negative individuals living in Africa also exhibit chronic immune activation, reminiscent of that observed in HIV-1 infected individuals. It is characterized by increased levels of soluble immune activation markers, such as the cytokines interleukin (IL)-4, IL-10, TNF-α, and cellular activation markers including HLA-DR, CD-38, CCR5, coupled with reduced naïve and increased memory cells in CD4+ and CD8+ subsets. In addition, it is accompanied by low CD4+ T cell counts when compared to Europeans. There is also evidence that mononuclear cells from African infants secrete less innate cytokines than South and North Americans and Europeans in vitro. Chronic immune activation in Africans is linked to environmental factors such as parasitic infections and could be responsible for previously observed immune hypo-responsiveness to infections and vaccines. It is unclear whether the immunogenicity and effectiveness of anti-SARS-CoV-2 vaccines will also be reduced by similar mechanisms. A review of studies investigating this phenomenon is urgently required as they should inform the design and delivery for vaccines to be used in African populations.

Chronic Immune Activation among Treatment Naïve HIV/ HBV Coinfected Individuals from Southern India

Background : Chronic immune activation is one of the most widely recognized hallmarks of HIV infection. T-cells that express CD38+ and HLA-DR+ show poor proliferative potential, signal transduction, and increased apoptotic potential. This affects HIV pathogenesis and its outcome and further complicates with a coinfection like HBV. Method: Study Design: Cross-sectional. Blood samples were collected and analyzed for virological markers using ELISA for HBeAg and RT-PCR for HIV&HBV Viral load. Chronic immune activation markers of CD8+ and CD4+ T cells were measured by Flow cytometry for both HIV and HBV Results: There was a significant increase in HBV replication shown by higher HBV DNA (p=0.002), a higher proportion of HBeAg (p=0.0049), and lower CD4 counts (p=0.04) among HIV/HBV coinfected individuals, compared to the monoinfected groups. The frequencies of CD4+ CD38+ HLA-DR+ and CD8+ CD38+ HLA-DR+ in the HIV/HBV coinfection were significantly higher than HBV monoinfected group (P< 0.0001) and in the HIV monoinfected group (P < 0.0001). The Liver fibrosis score APRI and FIB-4, were higher in the coinfected group compared with HBV monoinfected group (0.67 vs 0.25, p = 0.0085; 3.48 vs 0.98, p = 0.0026), respectively. The cytokine levels of IL-17, Fas-L, TNF -α, IL-10, IL-2and Granzyme B were also measured and compared among the study groups. Conclusion: Our data suggest that HIV probably influences the immune activation of CD4+ and CD8+ T cells, and this may play a significant role in accelerating the disease outcome among HIV/HBV coinfected individuals.

Gut IgA Enhances Systemic IgG Responses to Pneumococcal Vaccines Through the Commensal Microbiota

The gut microbiota enhances systemic immunoglobulin G (IgG) responses to vaccines. However, it is unknown whether this effect involves IgA, a mucosal antibody that coats intestinal microbes. Here we found that gut IgA increased peripheral IgG responses to pneumococcal vaccines, as these responses were profoundly impaired in mice with global or mucosa-restricted IgA deficiency. The positive effect of IgA on vaccine-induced IgG production implicated gut bacteria. Indeed, IgG responses to pneumococcal vaccines were also defective in ex-germ free mice recolonized with gut microbes from mouse or human IgA-deficient donors. IgA exerted this IgG-enhancing effect by constraining the systemic translocation of intestinal commensal antigens, which caused chronic immune activation, including T cell overexpression of programmed death-1. This immune inhibitory receptor hindered vaccine-specific IgG production by eliciting functional B cell unresponsiveness, which was reverted by anti-programmed death-1 treatment. Thus, gut IgA is functionally interconnected with systemic IgG via intestinal microbes.

HIV-1 Nef-induced secretion of the proinflammatory protease TACE into extracellularvesicles is mediated by Raf-1, and can be suppressed by clinical protein kinase inhibitors

Chronic immune activation is an important driver of HIV-1 pathogenesis, and has been associated with the presence of tumor necrosis factor-α converting enzyme (TACE) in extracellular vesicles (EV) circulating in infected individuals. We have recently shown that activation of the Src-family tyrosine kinase Hck by HIV-1 Nef can trigger the packaging of TACE into EVs via an unconventional protein secretion pathway. Using a panel of HIV-1 Nef mutants and natural HIV-2 and SIV Nef alleles we now show that the capacity to promote TACE secretion depends on the superior ability of HIV-1-like Nef alleles to induce Hck kinase activity, whereas other Nef effector functions are dispensable. Strikingly, among the numerous Src-family downstream effectors, serine/threonine kinase Raf-1 was found to be necessary and alone sufficient to trigger secretion of TACE into EVs. These data reveal the involvement of Raf-1 in regulation of unconventional protein secretion, and highlight the importance of Raf-1 as a cellular effector of Nef, thereby suggesting a novel rationale for testing pharmacological inhibitors of the Raf-MAPK pathway to treat HIV-associated immune activation. IMPORTANCE Chronic immune activation contributes to the immunopathogenesis of HIV-1 infection, and is associated with poor recovery of the immune system despite potent antiretroviral therapy, which is observed in 10-40% drug-treated patients depending on the definition of immune reconstitution. We have previously shown that the HIV pathogenicity factor Nef can promote loading of the proinflammatory protease TACE into extracellular vesicles (EV), and the levels of such TACE-containing EVs circulating in the blood correlate with low CD4 lymphocyte counts in HIV patients receiving antiretroviral therapy. Here we show that Nef promotes uploading of TACE into EVs by triggering unconventional secretion via activation of the Hck/Raf/MAPK kinase cascade. We find that several pharmaceutical inhibitors of these kinases that are currently in clinical use for other diseases can potently suppress this pathogenic deregulation, and could thus provide a novel strategy for treating HIV-associated immune activation.

The Dark Side of the Force: When the Immune System Is the Fuel of Tumor Onset

Nowadays, it is well accepted that inflammation is a critical player in cancer, being, in most cases, the main character of the process. Different types of tumor arise from sites of infection or chronic inflammation. This non-resolving inflammation is responsible for tumor development at different levels: it promotes tumor initiation, as well as tumor progression, stimulating both tumor growth and metastasis. Environmental factors, lifestyle and infections are the three main triggers of chronic immune activation that promote or increase the risk of many different cancers. In this review, we focus our attention on tumor onset; in particular, we summarize the knowledge about the cause and the mechanisms behind the inflammation-driven cancer development.